Comparative Analysis of TNF-alpha, TNF-R1, and TNF-R2 in Patients with Low-impact Fractures Due to Osteoporosis

Objective  To analyze the serum levels of TNF-alpha and its TNF-R1 and TNF-R2 receptors in the blood of patients with low-impact fractures due to osteoporosis, comparing between genders and with healthy patients. Methods  The present study was conducted with a blood sample of 62 patients, divided into patients with osteoporosis and healthy patients. The results were obtained using the ELISA method. Cytokine concentrations were determined based on the absorbance values obtained. Results  Serum TNF-alpha levels were undetectable in female patients, while in males they were found only in one patient, with no significant difference. Similar results were found in the analyses of TNF-R1 and TNF-R2 levels, a significant increase in levels of TNF-alpha receptors in the groups of patients with osteoporosis compared with the control group in both sexes. There was no significant difference between the sexes in the dosage of both receptors within the group with osteoporosis. There was also a positive and significant correlation in the levels of TNF-R1 and TNF-R2 only in women. Conclusion The significant increase in TNF-R1 and TNF-R2 levels in women with osteoporosis suggest that the release and expression of these receptors may be contributing differently to the development of osteoporosis in men and women.

ATVB Distinguished Scientist Award: How Costimulatory and Coinhibitory Pathways Shape Atherosclerosis

OBJECTIVE

Immune cells play a critical role in atherosclerosis. Costimulatory and coinhibitory molecules of the tumor necrosis factor receptor and CD28 immunoglobulin superfamilies not only shape T-cell and B-cell responses but also have a major effect on antigen-presenting cells and nonimmune cells.

APPROACH AND RESULTS

Pharmacological inhibition or activation of costimulatory and coinhibitory molecules and genetic deletion demonstrated their involvement in atherosclerosis. This review highlights recent advances in understanding how costimulatory and coinhibitory pathways shape the immune response in atherosclerosis.

CONCLUSIONS

Insights gained from costimulatory and coinhibitory molecule function in atherosclerosis may inform future therapeutic approaches.

Adam17 Deficiency Promotes Atherosclerosis by Enhanced TNFR2 Signaling in Mice

OBJECTIVE

ADAM17 (a disintegrin and metalloproteinase 17) is a sheddase releasing different types of membrane-bound proteins, including adhesion molecules, cytokines, and their receptors as well as inflammatory mediators. Because these substrates modulate important mechanisms of atherosclerosis, we hypothesized that ADAM17 might be involved in the pathogenesis of this frequent disease.

APPROACH AND RESULTS

Because Adam17-knockout mice are not viable, we studied the effect of Adam17 deficiency on atherosclerosis in Adam17 hypomorphic mice (Adam17^ex/ex), which have low residual Adam17 expression. To induce atherosclerosis, mice were crossed onto the low-density lipoprotein receptor (Ldlr)-deficient background. We found that Adam17^ex/ex.Ldlr^-/- mice developed ≈1.5-fold larger atherosclerotic lesions, which contained more macrophages and vascular smooth muscle cells than wild-type littermate controls (Adam17^wt/wt.Ldlr^-/-). Reduced Adam17-mediated shedding led to significantly increased protein levels of membrane-resident TNFα (tumor necrosis factor) and TNFR2 (tumor necrosis factor receptor 2), resulting in a constitutive activation of TNFR2 signaling. At the same time, Adam17 deficiency promoted proatherosclerotic cellular functions, such as increased proliferation and reduced apoptosis in cultured macrophages and vascular smooth muscle cells and increased adhesion of macrophages to vascular endothelial cells. Because siRNA (small interfering RNA)-mediated knockdown of Tnfr2 rescued from aberrant proliferation and from misregulation of apoptosis in Adam17-depleted cells, our data indicate that TNFR2 is an important effector of ADAM17 in our mouse model.

CONCLUSIONS

Our results provide evidence for an atheroprotective role of ADAM17, which might be mediated by cleaving membrane-bound TNFα and TNFR2, thereby preventing overactivation of endogenous TNFR2 signaling in cells of the vasculature.

IL-10 and ET-1 as biomarkers of rheumatic valve disease

OBJECTIVE

To evaluate the immunological profile and gene expression of endothelin-1 (ET-1) in mitral valves of patients with rheumatic fever originated from a reference service in cardiovascular surgery.

METHODS

This was a quantitative, observational and cross-sectional study. Thirty-five subjects (divided into four groups) participated in the study, 25 patients with chronic rheumatic heart disease and ten control subjects. The mean age of the sample studied was 34.5 years. Seventeen of them (48.58%) were male and 18 (51.42%) were female. Inflammatory cytokines (TNF-α, IL-4 and IL-10) were measured and ten mitral valves of patients who underwent first valve replacement were collected for determination of gene expression of endothelin-1 by real time PCR.

RESULTS

Among the groups studied (patients vs. controls), there was a statistically significant difference in IL-10 levels (P=0.002), and no differences in other cytokines. Expression of endothelin-1 was observed in 70% of samples. Quantitatively, average of ET-1 expression was 62.85±25.63%.

CONCLUSION

Inflammatory cytokine IL-10 participates in the maintenance of chronicity of rheumatic fever in patients who underwent valve replacement and those who are undergoing medical treatment. The expression of endothelin-1 in heart valve lesions in patients undergoing mitral valve replacement confirms its association with inflammatory activity in rheumatic fever.